$ git clone -n https://src.fedoraproject.org/rpms/bfs.git /var/lib/mock/f42-build-side-1-3499830-45966/root/chroot_tmpdir/scmroot/bfs
Cloning into '/var/lib/mock/f42-build-side-1-3499830-45966/root/chroot_tmpdir/scmroot/bfs'...
$ git fetch origin 058677331050a399e1de652d2b182ebe4fa01b8d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/bfs
 * [new ref]         058677331050a399e1de652d2b182ebe4fa01b8d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0586773 Update to 4.0.6 (rhbz#2338786)